/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.predictionio.controller

import org.apache.predictionio.core.BaseAlgorithm

/** A concrete implementation of [[LServing]] returning the average of all
  * algorithms' predictions, where their classes are expected to be all Double.
  *
  * @group Serving
  */
class LAverageServing[Q] extends LServing[Q, Double] {
  /** Returns the average of all algorithms' predictions. */
  def serve(query: Q, predictions: Seq[Double]): Double = {
    predictions.sum / predictions.length
  }
}

/** A concrete implementation of [[LServing]] returning the average of all
  * algorithms' predictions, where their classes are expected to be all Double.
  *
  * @group Serving
  */
object LAverageServing {
  /** Returns an instance of [[LAverageServing]]. */
  def apply[Q](a: Class[_ <: BaseAlgorithm[_, _, Q, _]]): Class[LAverageServing[Q]] =
    classOf[LAverageServing[Q]]
}
